A recent analysis of 17 studies suggests that owning a cat may double the risk of developing schizophrenia-related conditions. The research, led by psychiatrist John McGrath and his team at the Queensland Centre for Mental Health Research in Australia, reviewed studies published over the past 44 years across 11 countries, including the United States and the United Kingdom.
The findings indicate a “significant positive association” between cat ownership and an increased risk of schizophrenia-related disorders. The study emphasizes the need for more rigorous investigations in this area to clarify the connection. The results were published in the Schizophrenia Bulletin in December 2023.
The potential link between cat ownership and schizophrenia was first suggested in a 1995 study, which proposed exposure to a parasite known as Toxoplasma gondii as a possible cause. This parasite, typically transmitted through undercooked meat, contaminated water, or contact with infected cat feces, is believed to infect approximately 40 million people in the US, often without any noticeable symptoms.
As the researchers delve into the implications of their findings, they highlight a mixture of conclusions drawn from existing studies. While some suggest that childhood exposure to cats might increase the likelihood of developing schizophrenia, others have not found a consistent association. Some studies indicate that interactions with cats correlate with higher scores on scales measuring traits related to schizophrenia and psychotic-like experiences, yet other studies have shown no such link.
To gain a clearer understanding of the relationship between cat ownership and mental health, McGrath and his colleagues call for comprehensive reviews and analyses of all relevant research. They note that while their findings show individuals exposed to cats have approximately double the odds of developing schizophrenia, the nature of the research poses limitations.
Most of the studies reviewed were case-control designs, which do not establish cause and effect relationships and often fail to account for confounding factors. Furthermore, the researchers pointed out that many of the studies they examined lacked sufficient quality, with results varying significantly across different investigations.
One study noted no significant association between owning a cat before the age of 13 and later developing schizophrenia. However, it did find a notable link when narrowing the focus to specific ages, particularly between 9 and 12 years old. Such inconsistencies point to an undefined critical window for cat exposure regarding mental health outcomes.
Another investigation involving 354 psychology students in the US found no correlation between cat ownership and scores on a test measuring schizotypy. Nonetheless, individuals who had experienced a cat bite scored higher in comparison to those without such exposure. Additionally, a separate study that included participants with and without mental disorders identified a connection between cat bites and elevated scores on psychological assessment tests, but suggested that other pathogens, such as Pasteurella multocida, might be responsible for these effects.
Given the complexity of the data, McGrath’s team reiterates the urgent need for more high-quality studies with larger, representative samples. They assert, “Our review provides support for an association between cat ownership and schizophrenia-related disorders,” while emphasizing the importance of understanding cat ownership as a potential risk-modifying factor for mental health issues.
As research continues to explore the implications of pet ownership on mental health, the findings underscore the necessity for further investigation into the nuances of these associations.
